Trowel for pipe lining material



Oct. 1, 1963 w. E. PERKINS 3,105,282

TROWEL FOR PIPE LINING MATERIAL Filed Dec. 8, 1961 INVENTOR. Warren E Parkms,

AT TORNE YS' United States Patent 3,165,282 TRGWEL FGR it???) LINKNG MATERlAL Warren E. Perkins, Grand Island, N.Y., assignor to Perkins Pipe Linings, inc, Grand Island, NCY. Filed lies. 8, 1961, Ser. No. 157,9ti2 '7 Claims. (Cl. 253$) This invention relates to pipe lining apparatus Wherein a protective coating of mortar or similar material in plastic condition is applied to the interior of a pipe and more particularly to a troweh'ng means for smoothing the surface of such an interior coating directly after the same has been applied to or deposited against the interior wall of a pipe.

My prior Letters Patent No. 2,924,867, dated February 16, 1960, and No. 2,987,794, dated June 13, 1961, show troweling apparatus for this general purpose wherein the trowel device is adapted to be drawn through underground pipe and the former patent in particular shows apparatus for depositing a continuous layer of mortar against the interior of the pipe and for smoothing the same by directly following the depositing apparatus with a troweling device. The present invention provides a new and improved troweling means for use in a similar manner.

The troweling means of the present invention is so arranged that the tractive force for drawing the same through the pipe is more simply and efiectively applied and is constructed and arranged to provide the required flexibility and resilient adjustability while still providing necessary and desirable self-sustaining qualities in a novel manner.

Speaking generally, the troweling unit of the present invention comprises a pair of resilient plate-like trowel par which together form a conical frustum and a resilient U-shaped strap which is fixed at its opposite ends to the two trowel parts at the small end of the conical frustum to connect the parts in a resilient manner and serve as a simple device for connecting the trowel to means for drawing the same through a pipe for troweling an interior plastic coating on the walls thereof.

The midpoint of the U-shaped resilient connecting strap is directly connected to the tractive means so that a close-coupled relationship between the depositing apparatus and the troweling apparatus is achieved, in contrast with the relatively long plural link arrangements of my prior patents. Furthermore, the elimination of pivot joints and links minimizes the possibility of the device becoming fouled with mortar and thus losing its flexible adjustability in whole or in part.

The combined resilience of the aforesaid three permanently fixed and connected members provides a trowel which is drawn through the pipe with the small end of the conical frustum first and with the flaring peripheral wall of the frustum adjacent to the large trailing end acting outwardly against the mortar or like plastic material which has been applied to the interior of the pipe to smooth the same.

The edges of the two trowel parts overlap along lines extending g nerally from the small to the large end of the trowel assembly and the overlap is in such direction that when the trowel is rotated in a given direction as it is moved through a pipe the outer overlapping portions trail" so as not to dig into the mortar surface or become fouled therein and in order to produce a smoothly troweled surface. One simple way of producing a slight rotational movement of the trowel during its travel through a pipe is described in my aforesaid Patent No. 2,924,867 as resulting from a. frictional rotational force deriving from the swivel connection of the trowel to the mortar applying rotor. v

The overlapped portions of the trowel plates are unconnected so that the conical frustum may contract yieldingly under external generally radial forces which result from the trowel being drawn through a pipe which has been interior ly coated with mortar. Viewed conversely the trowel will tend to expand resiliently outwardly against such coating to smooth the same as the trowel passes along under the joint spring forces of the trowel plates themselves and the connecting U-shaped spring member. In use the trowel means is subjected to a certain extent to temporary local deformations and deflections due to obstructions being encountered, such as service cocks and the like.

it is desired that the trowel maintain its circular shape even though the diameter of its large end may be caused to vary somewhat due to variations in pipe diameter or, more usually, variations in the thickness of the applied coating. The effect of employing and applying the general principles of construction of the trowel of the present invention is that radially inward forces against the same at various points about the periphery of the large end produce approximately equal or uniformly proportionate inward deflections of the trowel body, due primarily to the mutual yielding of the aforesaid three resilient parts which form the trowel per se, namely the two trowel plate and the resilient U-shaped connecting member.

The rod connections to the trowel members shown in my aforesaid prior patents are subject to binding and cocking action when the trowel is compressed and the present construction provides a smoother, simpler and safer resilient action which compensates for diameter variations in a much more satisfactory manner. Coil springs in particular build up pressure resistance as they compress whereas the present U-shaped bow member offers substantially uniform resistance under deformation.

A single specific embodiment of the princples of the present invention is illustrated in the accompanying drawing and described in detail in the following specification. However, it is to be understood that such embodiinent is by way of example only and that various mechanical modifications may be introduced without departing from the spirit of the invention, the scope of which is limited only as defined in the appended claims.

In the drawing:

FIG. 1 is :a longitudinal cross-sectional view through a pipe being lined by a pipe lining apparatus having in combination therewith a trowel element or component constructed in accordance with one form of the present invention;

FIG. 2 is an end elevational view of the troweling element of FIG. 1 viewed from the left-hand side of FIG. 1,

that is, from the trailing end of the troweling element;

and

FIG. 3 is an end elevational view of the troweling element of FIG. 1 viewed from the right-hand end, that is,

the leading end of the troweling element.

The apparatus for applying the coating material to the interior of the pipe as a plastic mix in the form of mortar or the like is well known in the present art and the details adapted to be drawn through a subterranean pipe 11 by a remote winch and cable means or the like, the movemeat of the machine 10 being to the right as viewed in FIG. 1 during pipe lining operation thereof.

Mortar is fed to machine 10 through a flexible conduit 12 and merely by way of example is applied to the interior surface of the pipe by a rotary distributor head 13 which discharges the mortar centrifugally as indicated at 14 to apply a more or less rough coating of mortar 15 to the interior of pipe ll. The thickness of the coating is governed by the rate of discharge from distributor head 13 and the rate of movement of the machine through the pipe.

The frusto-conical troweling element itself is designated generally by the numeral 16 and is connected to the pipe lining machine at its leading end to follow the same through the pipe being lined. The means by which the troweling element 16 is connected to the pipe lining machine proper or to any other desired draft means is novel and this connecting means cooperates intimately with the troweling element itself in supporting and holding the parts of the latter in proper form and position and for yieldably sustaining the same for the proper performance of the troweling function under the special conditions under .which devices of this class must operate and the special the drawings, the connection being at the small end of the troweling element, that is the leading end thereof.

Thus the three parts which comprise the troweling assembly, while capable of certain resilient movements and relative positional adjustments permitted by joint flexing of the several parts in response to pressures thereon as encountered in trowelin g somewhat varying surfaces, comprise a fixed unit with the three parts permanently connected to each other and not requiring adjustable connections, pivoted joints, or the like. This satisfactorily eliminates moving joints or connections which are normally subject to fouling or sticking due to accumulations of mortar, particularly when the latter dries and hardens.

The two trowel plate members 20 and 21 which comblue to form the firusto-conical troweling element 16 are each approximately semi-circular in transverse cross section, in fact slightly greater than semi-circular in transverse extent so that they overlap as clearly shown in FIG. 3. The overlapping end portions of each of the trowel plates 20 and 21 are designated 24 and 25, respectively, and in the present instance the overlap is such that the overlapping ends trail as the troweling element rotates in a clockwise direction as viewed in FIG. 3. To accentuateand insure the desired trailing action of the exposed edges of the overlapping end portions of the trowel plates 20 and 21 at the large end such edges are cut to form angles as indicated at 26 and 27, respectively, in FIGS. 1 and 3, the large end portion of the troweling element 16 being the end which is in contact with the mortar during normal troweli-ng operation;

The U-shaped connecting and supporting member 18 in the present instance comprises a flat strip of spring steel having a medial semi-circular portion and terminal leg portions which flare at the desired angle of divergence of the walls of the trowel plates 20 and 21. Spacer blocks 3G and 31 have arcuate surface portions which are welded, brazed or otherwise permanently attached to the interiors of the plates 20 and 21 at their small ends and the legs of the member 18 are in turn welded, brazed or otherwise permanently attached to the opposite surfaces of the spacer blocks 36 and 31. Thus the member 18 resiliently supports the plates 20 and 21 in the desired free initial position illustrated in FIGS. 2 and 3 and the entire trowel assembly is compressible in diametral directions by the distributing head 13. The swivel connection permits the trowel element 16 to remain substantially stationary despite the rapid rotation of the head 13. Nevertheless under ordinary conditions moderate friction in the swivel connection 34 will result in slow rotation of the trowel element in a clockwise direction as indicated earlier herein, which rotation is beneficial rather than otherwise although it is not essential to the production of satisfactory trowelin g results.

Where local extraneous spring devices of one kind or another are attached to the interior of a troweling element of the type here under consideration for applying expanding force thereto the problem of applying such local force in a way to maintain a general circularity of the troweling element is difficult if not insoluble. If the troweling element does not possess the present inherent tendency to maintain circularity throughout its expanse, then if there be an increase in the thickness of the applied coating causing a contracting force upon the trowel, the latter may contract into a somewhat elliptical form which will produce a similarly elliptical interior surface of the applied coating and a consequent variation in the thickness thereof at various points about the wall of the pipe.

The above described relationship between the trowel plates and the U-shaped support member provides a construction which will tend to maintain generally true circularity as the trowel plates are flexed to different diameters by pressure of mortar bearing generally radially inwardly thereagainst. Nevertheless, the trowel may flex locally when acted upon by local forces such as obstructions projecting inwardly from the pipe wall and the trowel may freely assume a somewhat elliptical form when the pipe through which it is passing presents such form, which may be particularly when traversing curving portions of pipe.

I claim:

1. Trowel means for smoothing a layer of mortar in an interior generally cylindrical surface, said trowel means comprising a resilient sheet material body portion defining a frusto-conical tapering trowel body, said frusto-conical body comprising a pair of resilient plate portions overlapping at diametrically opposite portions along lines extending generally from the small to the large end of said frusto-conical body, a support for said plate portions comprising a U-shaped resilient strap member having a curved medial portion comprising the leading end of said trowel means and rearwardly flaring leg portions fixed to the interiors of said plate portions at the small end of said frusto-conical body and substantially medially of each plate portion in a circumferential direction, whereby said trowel means may be contracted diametrally against the joint resilient resistance of said plate portions and said support member.

2. Trowel means for smoothing a layer of mortar in an interior generally cylindrical surface, said trowel means comprising a resilient sheet material body portion defining a frusto-conical tapering trowel body, said frusto-conical body comprising a pair of resilient plate portions having their longitudinal edges contiguous along diametrically opposed lines extending generally from the small to the large end of said frusto-conical body, a support. for said plate portions comprising a U-shaped resilient strap member having a curved medial'portion comprising the leading end of said trowel means and rearwardly flaring leg portions fixed to the interiors of said plate portions at the small end of said fiusto-conical body andsubstantially medially of each plate portion in a circumferential direction, whereby said trowel means may be contracted joint yieldability of the plates themselves and the support 7 diametrally against the joint resilient resistance of said plate portions and said support member.

3. Trowel means for smoothing a layer of mortar in an interior generally cylindrical surface, said trowel means comprising a resilient sheet material body portion definresilient plate portions having their longitudinal edges overlapping along lines extending generally from the small to the large end of said frusto-conical body, a support for said plate portions comprising a U-shaped resilient strap member having a curved medial portion comprising the leading end of said trowel means and rearwardly flaring leg portions fixed to the interiors of said plate portions at the small end of said frustoconical body and substantially medially of each plate portion in a circumferential direction, whereby said trowel means may be contracted diametrally against the joint resilient resistance of said plate portions and said support member.

4. Trowel means for smoothing a layer of mortar in an interior generally cylindrical surface, said trowel means comprising a resilient sheet material body portion defining a frusto-conical tapering trowel body, said frusto-conical body comprising a pair of resilient plate portions overlapping at diametrically opposite portions along lines extending generally from the small to the large end of said frusto-conical body, a support for said plate portions comprising a U-shaped resilient strap member having a curved medial portion comprising the leading end of said trowel means and rearwardly flaring leg portions fixed to the interiors of said plate portions at the small end of said frusto-conical body and substantially medially of each plate portion in a circumferential direction, whereby said trowel means may be contracted diametrally against the joint resilient resistance of said plate portions and said support member, and means connecting to the midpoint of said U-shaped member for drawing the trowel means in an axial direction without restraining said joint resilience.

5. Trowel means for smoothing a layer of mortar in an interior generally cylindrical surface, said trowel means comprising a resilient sheet material body portion defining a frusto-conical tapering trowel body, said frusto-conical body comprising a pair of resilient plate portions overlapping at diametrically opposite portions along lines extending generally from the small to the large end of said frusto-conical body, a support for said plate portions comprising a U-shaped resilient member having its terminal portions extending rearwardly and fixed to said plate portions at the small end of said frusto-conical body and substantially medially of each plate portion in a circumferential direction, whereby said trowel means may be contracted diametrally against the joint resilient resistance of said plate portions and said support member, and means connecting to the midpoint of said U-shaped member for drawing the trowel means in an axial direction without restraining said joint resilience.

6. Trowel means for smoothing a layer of mortar in an interior generally cylindrical surface, said trowel means comprising a resilient sheet material body portion defining a frusto-conical tapering trowel body, said frusto-conical body comprising a pair of resilient plate portions having their longitudinal edges contiguous along diametrically opposed lines extending generally from the small to the large end of said frusto-conical body, a support for said plate portions comprising a U-shaped resilient member having its terminal portions extending rearwardly and fixed to said plate portions at the small end of said frustoconical body and substantially medially of each plate portion in a circumferential direction, whereby said trowel means may be contracted diametrally against the joint resilient resistance of said plate portions and said support member, and means connecting to the midpoint of said U-shaped member for drawing the trowel means in an axial direction without restraining said joint resilience.

7. Trowel means for smoothing a layer of mortar in an interior generally cylindrical surface, said trowel means comprising a resilient sheet material body portion defining a frusto-conical tapering trowel body, said frusto-conical body comprising a pair of substantially semiconic resilient plate portions having their longitudinal edges overlapping along lines extending generally from the small to the large end of said frusto-conical body, a U-shaped resilient support member having its terminal portions extending rearwardly and fixed to said plate portions at the small end of said frusto-conical body and substantially medially of each plate portion in a circumferential direction, whereby said trowel means may be contracted diametrally against the joint resilient resistance of said plate portions and said support member, and means connecting to the midpoint of said U-shaped member for drawing the trowel means in an axial direction without restraining said joint resilience.

References Cited in the file of this patent UNITED STATES PATENTS 474,143 McKelvey May 3, 1892 1,160,033 Ambrose Nov. 9, 1915 1,246,532 tBosma Nov. 13, 1917 1,627,045 McGeehin May 3, 1927 2,498,325 Zemanek et al. Feb. 21, 1950 2,924,867 Perkins Feb. 16, 1960 

1. TROWEL MEANS FOR SMOOTHING A LAYER OF MORTAR IN AN INTERIOR GENERALLY CYLINDRICAL SURFACE, SAID TROWEL MEANS COMPRISING A RESILIENT SHEET MATERIAL BODY PORTION DEFINING A FRUSTO-CONICAL TAPERING TROWEL BODY, SAID FRUSTO-CONICAL BODY COMPRISING A PAIR OF RESILIENT PLATE PORTIONS OVERLAPPING AT DIAMETRICALLY OPPOSITE PORTIOINS ALONG LINES EXTENDING GENERALLY FROM THE SMALL TO THE LARGE END OF SAID FRUSTO-CONICAL BODY, A SUPPORT FOR SAID PLATE PORTIONS COMPRISING A U-SHAPED RESILIENT STRAP MEMBER HAVING A CURVED MEDIAL PORTION COMPRISING THE LEADING END OF SAID TROWEL MEANS AND REARWARDLY FLARING LEG PORTIONS FIXED TO THE INTERIORS OF SAID PLATE PORTIONS AT THE SMALL END OF SAID FRUSTO-CONICAL BODY AND SUBSTANTIALLY MEDIALLY OF EACH PLATE PORTION IN A CIRCUMFERENTIALLY DIRECTION, WHEREBY SAID TROWEL MEANS MAY BE CONTRACTED DIAMETRALLY AGAINST THE JOINT RESILIENT RESISTANCE OF SAID PLATE PORTIONS AND SAID SUPPORT MEMBER. 